The present invention relates to an apparatus for electrophotographic image formation which includes a fixing unit for fixing a toner image on a sheet.
A problem with the speedup of an apparatus for electrophotographic image formation is the prevention of the heat shortage in the fixing unit of the apparatus, because, if the number of sheets which pass through this unit per unit time is larger they take away more of the heat accumulated in the unit.
The heat shortage in the fixing unit could be prevented by supplying more power from a commercial power source to the apparatus. However, troublesome interior wiring work is required to raise the upper limit of the power supplied from the power source.
For example, each of JP 2004-286869 A and JP 2004-294554 A discloses a conventional apparatus for electrophotographic image formation, in which the condenser or accumulator supplies power to the fixing unit so as to prevent the heat shortage in this unit. According to these publications, it is possible to shorten the warm-up time for the fixing unit. This shortens the fast copy time for the apparatus, so that the apparatus is sped up.
It is preferable to prevent the heat shortage in the fixing unit of an apparatus for electrophotographic image formation in such a manner that the apparatus can perform printing without interruption for a longer period, because printing interruption is a nuisance. Therefore, it is preferable that more sheets pass through the fixing unit per unit time, and that the apparatus be able to perform printing without interruption for a longer period.
The object of the present invention is to provide an apparatus for image formation having a simple structure which prevents the power supply to the fixing unit of the apparatus from being short while the apparatus is doing printing without interruption.